It is narrated from Sayyiduna Abdullah bin Amr (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) said: "Whoever is turned back from something he needs by an evil omen has committed shirk (associated partners with Allah)." The Companions said: O Messenger of Allah, what is the expiation for that? He (peace and blessings be upon him) said: "You should say: 'Allahumma la tayra illa tayruka, wa la khayra illa khayruka, wa la ilaha illa anta' (O Allah, there is no omen except the omen You decree, there is no good except Your good, and there is none worthy of worship except You)."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 13635